Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States.
Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States.
Environ Sci Technol. 2023 Oct 24;57(42):15925-15935. doi: 10.1021/acs.est.3c03855. Epub 2023 Aug 30.
sp. strain 273 grows with medium-chain terminally fluorinated alkanes under oxic conditions, releases fluoride, and synthesizes long-chain fluorofatty acids. To shed light on the genes involved in fluoroalkane metabolism, genome, and transcriptome sequencing of strain 273 grown with 1,10-difluorodecane (DFD), decane, and acetate were performed. Strain 273 harbors three genes encoding putative alkane monooxygenases (AlkB), key enzymes for initiating alkane degradation. Transcripts of -2 were significantly more abundant in both decane- and DFD-grown cells compared to acetate-grown cells, suggesting AlkB-2 catalyzes the attack on terminal CH and CHF groups. Coordinately expressed with -2 was an adjacent gene encoding a fused ferredoxin-ferredoxin reductase (Fd-Fdr). Phylogenetic analysis distinguished AlkB that couples with fused Fd-Fdr reductases from AlkB with alternate architectures. A gene cluster containing an ()-2-haloacid dehalogenase () gene was up-regulated in cells grown with DFD, suggesting a possible role in the removal of the ω-fluorine. Genes involved in long-chain fatty acid biosynthesis were not differentially expressed during growth with acetate, decane, or DFD, suggesting the bacterium's biosynthetic machinery does not discriminate against monofluoro-fatty acid intermediates. The analysis sheds first light on genes and catalysts involved in the microbial metabolism of fluoroalkanes.
sp. strain 273 在有氧条件下以中链末端氟化烷烃为生长介质，释放氟化物，并合成长链氟脂肪酸。为了阐明与氟烷烃代谢、基因组和转录组有关的基因，对以 1,10-二氟癸烷（DFD）、癸烷和乙酸盐培养的 273 株进行了测序。273 株含有三个编码烷单加氧酶（AlkB）的基因，AlkB 是烷烃降解的起始关键酶。与乙酸盐生长的细胞相比，在癸烷和 DFD 生长的细胞中 -2 的转录本明显更为丰富，这表明 AlkB-2 催化末端 CH 和 CHF 基团的攻击。与 -2 协调表达的是一个相邻的基因，编码一个融合的铁氧还蛋白-铁氧还蛋白还原酶（Fd-Fdr）。系统发育分析将与融合的 Fd-Fdr 还原酶偶联的 AlkB 与具有替代结构的 AlkB 区分开来。含有 ()-2-卤代酸脱卤酶 () 基因的基因簇在以 DFD 生长的细胞中上调，表明其可能在去除 ω-氟方面发挥作用。在以乙酸盐、癸烷或 DFD 生长过程中，参与长链脂肪酸生物合成的基因没有差异表达，这表明细菌的生物合成机制不会区分单氟脂肪酸中间体。该分析首次揭示了氟烷烃微生物代谢中涉及的基因和催化剂。
